Implantable medical devices for producing a therapeutic result in a patient are well known. Examples of such implantable medical devices include drug infusion pumps, implantable neurostimulators, cardioverters, cardiac pacemakers, defibrillators and cochlear implants. Of course, it is recognized that other implantable medical devices are envisioned which utilize energy delivered or transferred from an external device.
A common element in all of these implantable medical devices is the need for electrical power in the implanted medical device. The implanted medical device requires electrical power to perform its therapeutic function, which may include driving an electrical infusion pump, providing an electrical neurostimulation pulse or providing an electrical cardiac stimulation pulse. This electrical power is derived from a power source.
Some implantable medical devices can receive electrical power transcutaneously through the use of inductive coupling. For instance, power can be transferred by inductively coupling an external primary coil that is positioned on or near the skin of a patient with a secondary coil that is coupled to, or included within, an implantable medical device. Current induced in the secondary coil may be used to store energy in a power source such as a rechargeable battery and/or could be used to directly power circuitry within the implantable device. Once recharged, the internal power source may be used to supply electrical power to the implanted medical device.
Many devices and techniques have been developed to provide transcutaneous energy to power an implantable medical device and/or to recharge a power source associated with the device. As previously noted, techniques generally employ a primary coil driven by an external power source.